The present invention relates to asset condition or health monitoring and more particularly to the monitoring of machines in service.
Asset health monitoring, commonly referred to as equipment health monitoring (EHM), is based around the premise of sensing a plurality of operational variables for an asset during use. The gathered data can be used to determine an operational state of the asset. Additionally the data can be processed to identify the current condition or health status of the equipment. The output of the EHM system provides information to an operator which can be used to manage the operation of the equipment, for example by controlling the equipment in a manner which is sympathetic to the condition of the equipment or else by scheduling suitable repair or maintenance work.
The level of sophistication of an EHM system is often determined by the value or complexity of the asset. More particularly, sophisticated EHM systems are most often implemented where the cost of maintenance work to be carried out on the assets is relatively high. This therefore demands that maintenance schedules are optimised so that maintenance can be carried out effectively at appropriate intervals and with minimal disruption to the asset operation.
Gas turbine engines are one example of an asset for which EHM systems are becoming crucial to efficient asset management. In contrast to more immediate control systems, EHM systems for gas turbine engines look for anomalies in the long term trends of measured engine parameters. It is known to undertake trending of process variables (measured parameters) in order to improve condition monitoring without necessitating additional sensors or processing. Examples of such trending are described in WO/2007/133,543. Methods for identifying features in received sensor data and determining a machine operation diagnosis from such features are disclosed in WO/2011/003688.
It is also known to receive sensor readings of operational parameters and to use those readings for the more immediate control of equipment, for example by way of one or more on-board control units. Such systems allow more-critical, automatic control of equipment substantially in real-time, as opposed to EHM systems which concern longer term trending and analysis of data. Accordingly the algorithms used to process the received data in such scenarios differ significantly.
It has been found that, when a system component, such as a sensor, is changed between instances of use of the equipment (i.e. in service) a disturbance in the data trend may be caused. This disturbance can look similar to an anomaly caused by an adverse operational event. Thus an adverse event alert may be output by the EHM system, causing effort to be expended in trying to identify the cause of the anomaly. Such an investigation must assess a possible change in asset operation that may have caused the alert as well as the possibility that a system component may have been changed (i.e. that the asset is otherwise operating normally).
Such investigations can be manually time consuming, due to the need to access service and maintenance records for the asset and/or contact a service engineer to determine any relevant system changes that may have occurred at the time of the anomaly, and cause uncertainty over the operational state of the asset in the interim.
It is generally known in the art that engineering components can be provided with RFID tags to allow identification of components within a system by reading data stored on the tag. However such systems are electronically complex and costly to implement. Every component in such a system would require a unique RFID tag in order to be able to identify a change. Furthermore, components in some assets, such as gas turbine engines, are required to operate in harsh environments, which may impede use the use of such electronics. Also complex wiring or wireless systems would need to be installed in addition to existing local networks for the asset, which can already present significant installation and/or maintenance costs.
It is an aim of the invention to provide an asset monitoring system for which component changes can be accommodated in a manner that is better suited to the operation of the monitoring system.